1. Technical Field
The present disclosure relates to electronic equipment where, for example, an operation parameter for operating a main body of the electronic equipment is set.
2. Description of the Related Art
One of the types of electronic equipment includes a frequency synthesizer using a digital process. This frequency synthesizer includes a circuit portion and a microcontroller. The circuit portion includes an analog circuit and a digital processing portion. The analog circuit includes a voltage-controlled oscillator. The digital processing portion performs a digital process in a part of a PLL loop. The microcontroller serves as a controller that controls the circuit portion. Examples of operation parameters for the frequency synthesizer include a computing parameter required for a digital process, a nominal frequency, a variable width of frequency, and similar parameter.
To set the operation parameter, the operation parameter is written to a non-volatile memory in the frequency synthesizer by the manufacturer. When the frequency synthesizer is powered on, the operation parameter in the non-volatile memory is read out to a register in the frequency synthesizer, and then the frequency synthesizer is operation-able state.
Meanwhile, if the user makes an unnecessary change to the operation parameter, which is not intended by the manufacturer, satisfactory operations may not be achieved. On the other hand, some operation parameters are required to be freely set by the user.
Japanese Unexamined Patent Application No. 2008-541591 discloses a technique where data is encrypted by a secure processor so that a third party cannot decipher the encrypted data. However, the method differs from that of the present disclosure.
[Patent Literature 1] Japanese Unexamined Patent Application No. 2008-541591